Govt. Exams
Entrance Exams
Multilevel inverters generate more voltage levels, creating a staircase waveform closer to sinusoid, resulting in lower THD and fewer harmonics compared to two-level inverters.
In line-commutated converters, commutation occurs naturally due to phase voltage transitions. Thyristor turns off when the anode voltage becomes negative relative to cathode.
Snubber capacitors provide a path for displacement current during switching transitions, clamping the voltage and reducing dv/dt stress on semiconductor devices.
Output LC filters attenuate high-frequency switching harmonics and reduce voltage rise time (dv/dt), protecting connected equipment like motors.
The gate-source (Cgs), gate-drain (Cgd), and drain-source (Cds) capacitances require energy to charge/discharge, causing switching losses and limiting frequency.
Maintaining constant V/f ratio ensures the magnetic flux in the motor remains constant across the speed range, preventing core saturation and maintaining torque capability.
In 120° conduction mode, each IGBT or switch conducts for 120° of the fundamental frequency cycle, reducing harmonics compared to 180° mode.
In flyback converters, energy is stored in the transformer core during ON time and transferred to the output during OFF time through the secondary winding.
GTO can be turned on and off by gate control and blocks voltage bidirectionally when off, making it suitable for AC circuit applications.
Reverse recovery time affects switching frequency limits, causes switching losses, and creates EMI. Fast recovery diodes are preferred in high-frequency applications.
